From the S2 Thunderbolt of 1994-95, the Buell S1 Lightning was a decrease in model number and price, but an improvement in many ways. Developed by Harley-Davidson engineer Erik Buell, the Buell bikes pioneered many innovative features but never denied their desire for the brute horsepower of the 1203cc Sportster engine.
Adjectives like pure, naked and muscular are used on the Buell S1, some comparing its single-minded design to the Ducati Monster. With the Buell features such as horizontal rear shock absorber, large diameter front brake disc, and isoplanar engine mounts, there is no denying the performance orientation of the 100 hp machine.
With under 1000 miles, this one seems mint. From the eBay listing:
944 miles, one owner. To include new battery, original cylinder assembly with pistons, original heads, original air filter assembly (motor upgraded prior to delivery), plus original and Corbin seats. Bike properly stored in heated shop.
There was a factory upgrade engine available in 1998, maybe that's what was installed on this bike, though there are countless H-D 1200 upgrades available. Also seen here is a cone filter instead of the factory Power Volume intake. The owner has upgraded to a Corbin seat but includes the factory piece. WP suspension, low maintenance belt drive, and Italian controls complete this innovative package. Blue trellis frame and orange bodywork have a good-natured effect on this thunder bike.